74 MARINE ALG 
is a tropical and subtropical genus, and has one hundred and 
fifty species. Two of these, 8. vulgare and S. Montagnet, are found 
as far north as Cape Cod. See Introduction, page 34. 
S. vulgare. Stems cylindrical; branches alternate; leaves long, 
narrow, toothed, with short stalk and midrib; minute dark spots on its 
surface; air-vessels small balls resembling berries set on stalks and 
usually tipped with a long point; receptacles small, twig-like forms 
in the axils of the leaves; color olive-brown; plant one foot to three 
or more feet long. Common in Long Island Sound. (Plate XVI.) 
S. Montagnei. This species resembles S. vulgare, but is more slender 
in all parts, and the receptacles are more elongated. From south of 
ape Cod. 
S. bacciferum. Particular interest attaches to this species from the 
fact that it is the one which forms the floating vegetation of the Sargasso 
Sea. It grows attached on the Florida Keys and in the West Indies. 
Specimens are sometimes carried by the currents northward, and are 
found washed ashore. It differs from S. vulgare in the leaves, which 
are thicker, more attenuated, and sharply toothed, and in having a 
greater number of air-vessels. A branch of this species brought from 
the Sargasso Sea had air-vessels so numerous and closely set that it 
resembled a bunch of small grapes. 
